The following relates to semiconductor fabrication. It finds particular application to forming features. More particularly, it is directed to forming features using jet-printing technology.
Traditionally, photolithography was commonly used to pattern features on semiconductors. However, jet-printing technology has become a viable alternative and can reduce costs by eliminating a need for photolithographic systems and/or equipment. With jet-printing (or digital lithography), a jet printer is used to produce a pattern using materials ejected from a print head. The printed pattern can either include various features such as electrodes or be a mask used for subsequent semiconductor processing steps such as etching, stripping, etc. The resulting masks are sometimes referred to as jet-printed etch masks.
A typical process employing jet-printed etch mask technology includes depositing a film to be patterned; jet printing a mask pattern on the film; etching the exposed area of the material; and stripping the mask. This results in relatively low-resolution features with a size limited to the printed drop size, which typically is about forty microns for conventional jet-printers. One approach to achieving smaller feature sizes (e.g., narrower widths) is to manufacture print heads with smaller print drop sizes. However, redesigning print heads can be costly and inefficient.
Piezoelectric jet print heads allow generation of lower droplet volumes. However, the small feature size desired for various fabrication processes is still difficult to achieve, for example, due to surface tension between the droplet and the wetted surface. Typically, complete wetting is needed to form a good contact in order to prevent undercutting of the printed mask. However, as the surface is wetted, the liquid droplet tends to spread out making it difficult to control feature size, which can results in undesirably large feature sizes. Decreasing wetting can result in unreliable patterning due to poor adhesion of the droplet to the substrate.
Thus, there is an unresolved need for improved jet-printing patterning techniques.